You're not giving us a lot to work with...
I'm not particularly good with the technical stuff, and for all I know someone will come along with the answer to your problem in the following 9 seconds, but if nobody does, then...
I think that for now you should narrow down the possible causes. Start a new project, if it still lags with the new project, chances are your computer is causing it, if not, a script in your current game might be the problem.